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/* $Id$ */

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/** @file map.cpp Base functions related to the map and distances on them. */

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#include "stdafx.h"

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#include "debug.h"

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#include "direction_func.h"

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#include "core/bitmath_func.hpp"

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#include "core/alloc_func.hpp"

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#include "core/math_func.hpp"

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#include "map_func.h"

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#if defined(_MSC_VER) && _MSC_VER >= 1400 /* VStudio 2005 is stupid! */

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/* Why the hell is that not in all MSVC headers?? */

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extern "C" _CRTIMP void __cdecl _assert(void *, void *, unsigned);

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#endif

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uint _map_log_x;     ///< 2^_map_log_x == _map_size_x

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uint _map_log_y;     ///< 2^_map_log_y == _map_size_y

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uint _map_size_x;    ///< Size of the map along the X

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uint _map_size_y;    ///< Size of the map along the Y

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uint _map_size;      ///< The number of tiles on the map

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uint _map_tile_mask; ///< _map_size - 1 (to mask the mapsize)

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Tile *_m = NULL;          ///< Tiles of the map

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TileExtended *_me = NULL; ///< Extended Tiles of the map

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/*!

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 * (Re)allocates a map with the given dimension

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 * @param size_x the width of the map along the NE/SW edge

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 * @param size_y the 'height' of the map along the SE/NW edge

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 */

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void AllocateMap(uint size_x, uint size_y)

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{

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	/* Make sure that the map size is within the limits and that

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	 * the x axis size is a power of 2. */

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	if (size_x < 64 || size_x > 2048 ||

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			size_y < 64 || size_y > 2048 ||

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			(size_x & (size_x - 1)) != 0 ||

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			(size_y & (size_y - 1)) != 0)

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		error("Invalid map size");

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	DEBUG(map, 1, "Allocating map of size %dx%d", size_x, size_y);

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	_map_log_x = FindFirstBit(size_x);

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	_map_log_y = FindFirstBit(size_y);

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	_map_size_x = size_x;

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	_map_size_y = size_y;

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	_map_size = size_x * size_y;

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	_map_tile_mask = _map_size - 1;

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	free(_m);

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	free(_me);

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	/* XXX @todo handle memory shortage more gracefully

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	 * CallocT does the out-of-memory check

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	 * Maybe some attemps could be made to try with smaller maps down to 64x64

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	 * Maybe check for available memory before doing the calls, after all, we know how big

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	 * the map is */

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	_m = CallocT<Tile>(_map_size);

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	_me = CallocT<TileExtended>(_map_size);

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}

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#ifdef _DEBUG

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TileIndex TileAdd(TileIndex tile, TileIndexDiff add,

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	const char *exp, const char *file, int line)

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{

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	int dx;

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	int dy;

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	uint x;

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	uint y;

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	dx = add & MapMaxX();

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	if (dx >= (int)MapSizeX() / 2) dx -= MapSizeX();

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	dy = (add - dx) / (int)MapSizeX();

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	x = TileX(tile) + dx;

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	y = TileY(tile) + dy;

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	if (x >= MapSizeX() || y >= MapSizeY()) {

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		char buf[512];

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		snprintf(buf, lengthof(buf), "TILE_ADD(%s) when adding 0x%.4X and 0x%.4X failed",

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			exp, tile, add);

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#if !defined(_MSC_VER) || defined(WINCE)

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		fprintf(stderr, "%s:%d %s\n", file, line, buf);

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#else

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		_assert(buf, (char*)file, line);

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#endif

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	}

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	assert(TileXY(x, y) == TILE_MASK(tile + add));

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	return TileXY(x, y);

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}

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#endif

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/*!

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 * Scales the given value by the map size, where the given value is

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 * for a 256 by 256 map.

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 * @param n the value to scale

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 * @return the scaled size

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 */

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uint ScaleByMapSize(uint n)

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{

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	/* First shift by 12 to prevent integer overflow for large values of n.

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	 * >>12 is safe since the min mapsize is 64x64

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	 * Add (1<<4)-1 to round upwards. */

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	return (n * (MapSize() >> 12) + (1 << 4) - 1) >> 4;

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}

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/*!

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 * Scales the given value by the maps circumference, where the given

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 * value is for a 256 by 256 map

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 * @param n the value to scale

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 * @return the scaled size

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 */

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uint ScaleByMapSize1D(uint n)

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{

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	/* Normal circumference for the X+Y is 256+256 = 1<<9

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	 * Note, not actually taking the full circumference into account,

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	 * just half of it.

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	 * (1<<9) - 1 is there to scale upwards. */

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	return (n * (MapSizeX() + MapSizeY()) + (1 << 9) - 1) >> 9;

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}

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/*!

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 * This function checks if we add addx/addy to tile, if we

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 * do wrap around the edges. For example, tile = (10,2) and

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 * addx = +3 and addy = -4. This function will now return

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 * INVALID_TILE, because the y is wrapped. This is needed in

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 * for example, farmland. When the tile is not wrapped,

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 * the result will be tile + TileDiffXY(addx, addy)

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 *

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 * @param tile the 'starting' point of the adding

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 * @param addx the amount of tiles in the X direction to add

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 * @param addy the amount of tiles in the Y direction to add

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 * @return translated tile, or INVALID_TILE when it would've wrapped.

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 */

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TileIndex TileAddWrap(TileIndex tile, int addx, int addy)

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{

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	uint x = TileX(tile) + addx;

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	uint y = TileY(tile) + addy;

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	/* Are we about to wrap? */

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	if (x < MapMaxX() && y < MapMaxY())

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		return tile + TileDiffXY(addx, addy);

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	return INVALID_TILE;

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}

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/** 'Lookup table' for tile offsets given a DiagDirection */

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extern const TileIndexDiffC _tileoffs_by_diagdir[] = {

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	{-1,  0}, ///< DIAGDIR_NE

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	{ 0,  1}, ///< DIAGDIR_SE

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	{ 1,  0}, ///< DIAGDIR_SW

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	{ 0, -1}  ///< DIAGDIR_NW

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};

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/** 'Lookup table' for tile offsets given a Direction */

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extern const TileIndexDiffC _tileoffs_by_dir[] = {

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	{-1, -1}, ///< DIR_N

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	{-1,  0}, ///< DIR_NE

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	{-1,  1}, ///< DIR_E

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	{ 0,  1}, ///< DIR_SE

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	{ 1,  1}, ///< DIR_S

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	{ 1,  0}, ///< DIR_SW

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	{ 1, -1}, ///< DIR_W

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	{ 0, -1}  ///< DIR_NW

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};

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/*!

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 * Gets the Manhattan distance between the two given tiles.

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 * The Manhattan distance is the sum of the delta of both the

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 * X and Y component.

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 * Also known as L1-Norm

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 * @param t0 the start tile

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 * @param t1 the end tile

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 * @return the distance

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 */

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uint DistanceManhattan(TileIndex t0, TileIndex t1)

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{

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	const uint dx = Delta(TileX(t0), TileX(t1));

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	const uint dy = Delta(TileY(t0), TileY(t1));

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	return dx + dy;

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}

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/*!

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 * Gets the 'Square' distance between the two given tiles.

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 * The 'Square' distance is the square of the shortest (straight line)

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 * distance between the two tiles.

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 * Also known as euclidian- or L2-Norm squared.

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 * @param t0 the start tile

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 * @param t1 the end tile

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 * @return the distance

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 */

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uint DistanceSquare(TileIndex t0, TileIndex t1)

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{

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	const int dx = TileX(t0) - TileX(t1);

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	const int dy = TileY(t0) - TileY(t1);

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	return dx * dx + dy * dy;

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}

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/*!

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 * Gets the biggest distance component (x or y) between the two given tiles.

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 * Also known as L-Infinity-Norm.

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 * @param t0 the start tile

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 * @param t1 the end tile

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 * @return the distance

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 */

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uint DistanceMax(TileIndex t0, TileIndex t1)

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{

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	const uint dx = Delta(TileX(t0), TileX(t1));

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	const uint dy = Delta(TileY(t0), TileY(t1));

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	return max(dx, dy);

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}

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/*!

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 * Gets the biggest distance component (x or y) between the two given tiles

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 * plus the Manhattan distance, i.e. two times the biggest distance component

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 * and once the smallest component.

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 * @param t0 the start tile

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 * @param t1 the end tile

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 * @return the distance

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 */

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uint DistanceMaxPlusManhattan(TileIndex t0, TileIndex t1)

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{

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	const uint dx = Delta(TileX(t0), TileX(t1));

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	const uint dy = Delta(TileY(t0), TileY(t1));

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	return dx > dy ? 2 * dx + dy : 2 * dy + dx;

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}

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/*!

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 * Param the minimum distance to an edge

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 * @param tile the tile to get the distance from

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 * @return the distance from the edge in tiles

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 */

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uint DistanceFromEdge(TileIndex tile)

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{

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	const uint xl = TileX(tile);

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	const uint yl = TileY(tile);

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	const uint xh = MapSizeX() - 1 - xl;

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	const uint yh = MapSizeY() - 1 - yl;

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	const uint minl = min(xl, yl);

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	const uint minh = min(xh, yh);

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	return min(minl, minh);

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}

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/*!

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 * Function performing a search around a center tile and going outward, thus in circle.

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 * Although it really is a square search...

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 * Every tile will be tested by means of the callback function proc,

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 * which will determine if yes or no the given tile meets criteria of search.

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 * @param tile to start the search from. Upon completion, it will return the tile matching the search

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 * @param size: number of tiles per side of the desired search area

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 * @param proc: callback testing function pointer.

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 * @param user_data to be passed to the callback function. Depends on the implementation

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 * @return result of the search

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 * @pre proc != NULL

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 * @pre size > 0

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 */

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bool CircularTileSearch(TileIndex *tile, uint size, TestTileOnSearchProc proc, void *user_data)

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{

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	uint n, x, y;

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	DiagDirection dir;

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	assert(proc != NULL);

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	assert(size > 0);

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	x = TileX(*tile);

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	y = TileY(*tile);

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	if (size % 2 == 1) {

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		/* If the length of the side is uneven, the center has to be checked

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		 * separately, as the pattern of uneven sides requires to go around the center */

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		n = 2;

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		if (proc(TileXY(x, y), user_data)) {

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			*tile = TileXY(x, y);

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			return true;

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		}

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		/* If tile test is not successful, get one tile down and left,

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		 * ready for a test in first circle around center tile */

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		x += _tileoffs_by_dir[DIR_W].x;

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		y += _tileoffs_by_dir[DIR_W].y;

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	} else {

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		n = 1;

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		/* To use _tileoffs_by_diagdir's order, we must relocate to

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		 * another tile, as we now first go 'up', 'right', 'down', 'left'

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		 * instead of 'right', 'down', 'left', 'up', which the calling

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		 * function assume. */

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		x++;

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	}

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	for (; n < size; n += 2) {

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		for (dir = DIAGDIR_NE; dir < DIAGDIR_END; dir++) {

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			uint j;

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			for (j = n; j != 0; j--) {

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				if (x <= MapMaxX() && y <= MapMaxY() && ///< Is the tile within the map?

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						proc(TileXY(x, y), user_data)) {     ///< Is the callback successful?

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					*tile = TileXY(x, y);

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					return true;                        ///< then stop the search

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				}

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				/* Step to the next 'neighbour' in the circular line */

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				x += _tileoffs_by_diagdir[dir].x;

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				y += _tileoffs_by_diagdir[dir].y;

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			}

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		}

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		/* Jump to next circle to test */

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		x += _tileoffs_by_dir[DIR_W].x;

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		y += _tileoffs_by_dir[DIR_W].y;

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	}

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	*tile = INVALID_TILE;

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	return false;

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}